Tuesday, August 14, 2018

MMAC Contest & Model Trim

Why do some planes fly pretty consistent day after day while others seem to vary? I thought using a covering that changes a great deal with humidity was the major part of it but it seems there is more to it than that. I have to believe the aerodynamics of some planes results in a plane that has greater stability and the plane is a little more tolerant in slight variations in the trim. I know wood changes with weather conditions and I would assume plastic does to a smaller extent. Many years ago when I first started flying radio control glow planes I remember people warning about the plastic pushrods and how they would change with temperature. The speed of the aircraft multiplies the trim issues. 

Streak Landed on Sandy Road

As I build new planes I go to the extra effort to build in screw adjustments for rudder and stabilizer. I find that I am making small adjustments on different days; it is not just get one trim adjustment and leave it forever. Sometimes it seems the trim changes throughout the day. 

My goal with my competition free flight models has been just to get consistent flights so I can get as much experience as possible without breaking it. After three years I am starting to think more about the performance. Recently I have been working with ½ A Streak glow model. Throughout the first several flying sessions I worked getting a consistent climb and transition. Some of the short first flights were rather nerve racking, on a couple of occasions the plane did a loop after launch, one time it pulled out just as it hit the ground.

Dave B at North Branch

With a washin wedge on inside right panel and tiny amount of right rudder some of the time, the power pattern is good and the plane transitions well. The issue now is it comes down too darn fast, at first I thought I was just launching into bad air but that cannot be the case on every flight. My theory now is the plane is just too heavy; it weighs 6 ounces while other people have built the plane to slightly less than 5 ounces. My Basic Yeller Pee Wee 30 model which has slightly less wing area weighs much less than 4 ounces; a big difference. 

Wilbur Folded Wing

At the last contest I attended near North Branch Minnesota on my second official flight of my Wilbur rubber model the wing folded right after launch. Between the test flight, the first official flight I had added a larger number of turns to the rubber but less than I have used in the past. The wing structure is minimal so I will try to strengthen it without adding too much weight. Even with a big boxy fuselage this model glides pretty well.

More Dramatic Wing Folding

Flew discus launch glider and catapult in the contest as well, with the discus I was getting good altitude compare to others but just couldn’t seem to get the glider in a thermal it could stay with. My catapult glider that I struggled with and broke so many times is now flying consistent.

For a small contest there were several people flying towline glider, as it had gotten windy I did not attempt to fly my Jetstream towline. If you had a good flight there was a good chance it could land in a tree.

Bill Kuhl

Wednesday, August 8, 2018

Nats Concluded - Finally a Winner

At least one person remarked I packed a lot of airplanes in my small car; I flew most of them but not all in competition. My Jetstream towline glider I never took out of the car. I flew my Wilbur rubber model just for fun but ran out of time to fly it Friday in competition. Friday I had too many events; P30 rubber, PeeWee 30 gas, hi-start glider, classic towline and OT Stick rubber. The last two I never flew, there was about an hour left Friday afternoon and that is not enough time if you are walking. Tuesday evening I ran the E20 event for Bob Stalick but did not fly. Taking pictures, video, and recording scores kept me plenty busy. I had created a scoring spreadsheet for my tablet which worked fine but it is hard to see a screen in sunlight.

Basic Yeller Pee Wee 30
E20 Event Tuesday Evening

Friday morning started with very little wind, I wanted to fly my Polecat X p30 model first because it uses a long 3/32” rubber motor that runs a long time but climbs slowly, good for calm conditions. I had test flown it the day before and a strand of rubber broke, so I replaced the motor. The first contest flight I wound to 1200 turns and the plane barely flew. I tried winding to 1550 turns and the motor broke every strand in the rear. To speed up things I tried tying the strands together, it broke in front this time. New motor from same batch of rubber I carefully wound to 1500 turns.

Polecat X P30

I launch the model and it was stalling like crazy and came down, one attempt. In my stress to get in another flight I put a shim on the rear of the stab instead of the front. It stalls even worse, another attempt. Fix the shim and wind the motor to 1500 turns and the plane is flying better but bouncing around in the wind that is increasing. My last flight took it across the field almost to the camp ground but the duration was short of a max. It just seems to me the previous batch of rubber I used in the plane worked better.

Wilbur Rubber Model

On to my next event PeeWee 30, my Basic Yeller has had many flights just for fun but never flown in competition. The first launch it had a little too much right and not enough rpm and hit the ground breaking the pylon. I glued that up and flew two hand launched flights that were around a minute long. For the last flight I had the motor adjusted better which it needed because the last flight was the ROG flight. I was afraid it might hit a tree going into the wind but it turned back and provided another long walk down the field.  There were 6 people signed up for the event and only 3 flew. I won my first trophy at the Nats and it was for first place. Having my name called in award ceremony for the first time in three years was nice.

Retro Gnome Hi-start Glider
Models Brought to Nats
The last event I flew was not an official event but fun just the same, hi-start glider. One evening I had flown the Retro Gnome glider I had built a couple of years ago using 1/16” rubber on the hi-start instead of 1/8” rubber which is really too much. With the thinner rubber the glider appears to adjust the flight path to straight better than when it launches too fast. Flying in the contest it was gusty but my glider launched without crashing every time. The last flight I think I stretched the rubber a little too much and the glider had a little trouble releasing. One flight resulted in a rather long chase but duration was not great in any of the flights. I was just happy how well it launches.

2018 Sympo

This concludes comments on my trip to the 2018 Free Flight Nats, it sure was a great time that went too fast. I really would have liked to have been more social but it was great getting so much flying in. The 2018 NFFS Sympo was for sale at the Nats, I have two articles in this issue. One is on recruiting kids to free flight and the other is on viscous DT timers.

Bill Kuhl

Monday, August 6, 2018

Nats 2018 Adventures II

Monday morning early there was barely any wind and I thought I could no longer put off flying the Witch Hawk 500 I had built, having completed it not long before the Nats. This was my first larger glow powered free flight with 60” wingspan powered by an old K&B .19 Greenhead. I was really nervous to fly the model but then I didn’t build it to hang from ceiling. This was the first time using bladder pressure and using an electric starter strapped to a stand. If there wasn’t so much equipment needed I would have flown it far from the flightline. 

I Had a Before Picture Taken

First Flight

First short flight it climbs completely straight and stalls. The wing pops off but only damage was a broken propeller. Adjusted the rudder a tiny amount to the right, next flight it climbs slightly right and transitions great. With no wind to drift it the glide circle was going right over the cars and people. I was so afraid it would hit a car but instead it hit a golf cart breaking the wing in half, worse than that it broke the Texas Timers Max IIIa timer. I have the wing almost repaired except for covering.

Super Pearl E-202
Wednesday was the E36 event and I flew the first e36 I built the Super Pearl e202 which is still flying well. Except on the first launch I did not have the stab adjustment screw on the platform, the plane went up rather flat and the glide was a dive, luckily no damage. My next two official flights were okay but short of a max. On the last flight the Pearl makes a huge circle around the edges of the field, I lost sight of where it landed but I had my tracker. This was my chance to use the tracker; I get a rather strong signal from the area by the two metal buildings across the field. 

Dave Comes to the Rescue

As I walk by the buildings I see at least two models but not mine. A guy cutting grass tells me there is a model in the next field beyond the buildings. I walk over there and these were high-tech FAI models, so I walk back towards the camp grounds. By now I am really doubting by ability to use the tracker; Dave Sechrist drives by on his little Honda motorcycle. He thought it could be by campground but drove in that direction and found nothing. It has to be towards the buildings and in a short jaunt on his cycle he found my plane real close to a building. He offered a ride back on the rack of his motorcycle and I accepted. Later I checked my smartphone as to how far I walked that day and it was a little over 14 miles. At least the flight was a max but my only one. What rather shocked me was looking at the results how even experts had poor flights that day.

Not just sure what I flew after that, I think it was catapult glider. I was really tempted to skip the event but thought at least I would try. Still using the catapult glider that I had so much trouble getting to transition early in the 2018 season but it is still flying. I was actually happy the flights were rather short because I did not want to walk too far. As I ended a gentleman gave me some advice on launching which helped, the guy was Ralph Ray.

I stayed out to the field rather late as that was the NFFS banquet night. Really a great meal and program afterwards, I really like the funny speech Bob Hanford gives, and great choices for the Hall of Fame members. Think I need at least one more blog post to cover my Nats adventure.

Bill Kuhl

Wednesday, August 1, 2018

It Flew Great Back Home – Nats 2018

Last week was my third Free Flight Nats contest in Muncie Indiana; for the most part weather was good, I learned a great deal, and had a fantastic time. I came home with all the planes I brought but some repairs are needed on a couple of the planes. On arriving late Saturday afternoon in rainy weather, I still went out to the field and flew my Super Pearl e36 between rain showers, there was one other plane flying. Sunday is the day many people use for testing before the start of the contest on Monday; I spent the morning flying non-stop and did more observing in the afternoon as the wind increased. My ½ A Streak for One-Design had been flown on small field back home but only the last time out did I feel it was close to trimmed. The flights on Sunday morning looked good, with no sign of trying to loop as it had back home. 

1/2 A Streak

Saturday Evening Flying

In the afternoon I flew my Blue Ridge Special with DT a few times just for fun. The last flight it went a little further and I had a heck of time finding it in the grass. Thought I had a good line on it and so did someone else but it seems that the smaller models such as e20 or this model with 14” wingspan disappear easily in the longer grass. Luckily someone on a motorcycle found it for me; I put it away after that.

Bob with electric Satellite

The rest of the day I was observing Bob fly his e36 Satellite and Craig fly his Big Dog electric. Bob had a very nice looking e36 Satellite that was giving him fits to adjust but had flown well back home. I took video of the second short test flight and the model rolled inverted and crashed, damage was extensive.

Craig with Big Dog Electric

Craig had this well-built larger electric model that just didn’t want to transition properly, it starts on a nice right climb, then straightens out which cause it to stall after the motor cut. At this point it would either dive or do a tail slide.  Larry, Bob, and Jim, a combination of many years of free flight experience had Craig try all sorts of adjustments to thrust, rudder, etc. and it was not helping. After an adjustment had been put in it would be taken out and another adjustment tried. It did get better and I understand it did get sorted before contest flying but was destroyed after hitting something on the field.

Eureka E36

I flew my Eureka e36 many times but was noticing the trim change also. The wing mount appeared to be loose but after fixing it the issue appeared again. After making one official flight, it spiraled in to the right and broke the fuselage. Not an extensive repair needed but I am going to recover the wing with Polyspan Lite. I would have done this before but was running out of time before the contest. With no diagonal structure in the wing, I can image there can be flexing going on when tissue gets loose. I remember last year after a crash from a bad launch of my E36 Starduster the repaired wing would do funny things as the motor run was increased.  The ½ A Streak I covered with Polyspan Lite appeared to stay in trim well. It is not much more work, just that multiple coats of color and dope are needed.

 Just for fun I flew my Flying Aces Moth and it worked well but went back to old habit of crashing to the right, more fuselage repair is needed.

 Paul had a really squirrely flight with a very well built embryo model, it had flown great the day before. We have been discussing ideas of what differences were between the flying on two different days.

In conclusion, free flight can be even more challenging than I had thought. I learned much but also realize there is way more I do not know.  With the air conditions a big part of flight duration, even the experts have bad flights on occasion. 

Bill Kuhl


Monday, July 16, 2018

Nats Free Flight Next Week - Getting Ready

My summer has been really busy, yet I have not done as much as in past summers, or at least not a thing with students or demonstrations. The College for Kids program that I taught for many years is taking a breather this summer and planning for next year. I feel this summer I have been the student, trying to teach myself new things.  This winter I started building my first larger glow powered free flight, the Witch Hawk 500 from a BMJR kit. Building a larger balsa plane was not that hard for me in that I have built several wood RC sailplanes 2 meter or larger. What took more time was that I used an airbrush system to spray the Polyspan covering and had to spray two different types of dope with a color dye in between. The airbrush worked fine but it is a rather small system for spraying a plane that size.

Witch Hawk 500

Red Cap Bladder
Compressor for Spray Painting

This was the first time for me running a glow engine on a bladder pressure. I ran the motor first on suction on test stand and then tested a bladder made from plugging one end of tubing. It ran alright but it was easy to flood the engine.  I then tried a bladder made from a product to seal the end of a caulking gun known as “Red Cap”. This created a little less pressure but appears to work fine with my engine; K&B .19 Greenhead. I was told with more pressure it might be necessary to use a needle with finer threads, I purchased an OS .20 needle valve but have not used it. 

With an engine running on pressure I decided I needed an electric starter on a stand with a foot switch. From my glow RC planes I had a starter but needed it to be stationary. I found a small plastic foot stool that I attached the starter to and wired in the foot pedal switch designed for electric trolling motor. It seemed to work well when I started the motor on the plane. I have not flown it yet but did some test glides that looked good.

1/2 A Streak

My intentions were to build the two One Design models for the 2018 Nats Streak and Smarty, only the Streak was completed but the Smarty is well along.  Power for the Streak is a K&B .049 running on suction with the tank below the motor. I have run the motor several times and flown it more and it runs perfect.  The plane I think I am just getting adjusted properly, some of the first flights were rather exciting in that the plane banked too much right, stalled going straight up as motor quit or did a loop under power. Almost no damage and the last time out the climb was much better and it landed gently from the glide.

Eureka e36

New for this year was another e36 electric model the Eureka which is based on a glow model from the 1950’s. Trimming this model has gone pretty well except two times it went too much right after launch into the ground. Damage was minimal; I added more left thrust and have not had another crash. This past weekend I am guessing I made 20 flights with this plane. The rudder tab and stab are screw adjustable and I tried tiny tweaks to get power and glide patterns closer to ideal. 

It is my hope that I will do a little better in competition at the Nats this year but mainly just hope to learn more and see people I have not seen since last year.

Bill Kuhl

Friday, June 22, 2018

More Videos, Hopefully Better Video

I purchased a new computer this year with the main goal to create better videos, besides that my old computer was several years old and really slow. The new computer is tiny in size but powerful and runs really cool. After several years of publishing this blog I am amazed at how many views there have been over time, very close to 300,000 now.  If video is done well, I think it is more interesting than written articles. In that I am doing most of this by myself, it is rather hard to get images and video of model airplanes while flying at the same time.

The first videos will probably be more still images because that is what I have to tell the story. Besides model airplanes I hope to get back to more science and other videos. Mainly I just hope to keep learning, improve, and have fun. I have been thinking a lot about what makes an interesting story for the intended audience.  My most recent narrated video is a story about how I decided to build a free flight PeeWee 30 model and what I needed to learn. I have much to learn about narration and editing but will keep working on it.

Witch Hawk 500

I am really close to finishing up a couple of free flight models for the 2018 contest season. The Witch Hawk 500 is my first larger glow powered free flight using a K&B .19 engine for power. This is the first time running an engine on bladder pressure so I have been running it on a test stand. 

Almost completed is an E36 NOS free flight model, design by Don DeLoach of a classic glow model the Eureka. My skill level is still where I do not feel comfortable with really fast climbing airplanes, this should be more my speed.

Eureka E36 NOS

I have made one short flight with the 1/2 A Streak model built this winter, broke the fragile plastic prop and it started to rain so did not get anymore flights in.

1/2 A Streak

In the works are a couple of videos, one about free flight history and the older design models I have built because of my interest in model aviation history. Another video is about my model aviation history, and most of the different aspects of the hobby that I have enjoyed.

Bill Kuhl

Thursday, June 14, 2018

Fishing Distraction to Model Airplane Hobby

To me it seems like events that a person really looks forward to seem like forever in the future and then all of a sudden come very quickly.  In July I plan to compete again at the 2018 Free Flight Nats in Muncie Indiana. There are two models I am still finishing up construction on and another one that has not been test flown yet.  When the weather is nice I would rather go fishing or fly model airplanes. With the opening of Largemouth Bass season it seems like there is a week that the fish are pretty easy to catch, even the big ones. That time period has passed but I still like to try during the hour before sunset. RC sailplane flying I sneak in time flying my UMX Radian at a local park during lunch or right after work.

Evening Fishing
Installed New Motor in UMX Radian

For the first time I will have articles in the 2018 NFFS Symposium report coming out this summer. One article is about Viscous DT timers and the other is about recruiting youngsters to free flight model aviation.  I created a website article that is more of a tutorial about the theory on the science of how a viscous DT timer operates; the Symposium article is more about suggestions on more effectively using a viscous DT timer in a free flight model. For testing purposes I installed a viscous DT timer in a rather small sport model the Blue Ridge Special available in a 2 pack semi kit from Volare, construction of the second model is well along. It really did not add much weight to a 14” rubber model and it brings it down effectively by popping up the front of the wing. I have a short video on this and working on more videos somewhat like the blog reports.

Blue Ridge Special

For the first time I have almost completed a larger glow powered free flight, Witch Hawk 500 powered by a K&B .19.  This is my first time running a glow motor on bladder pressure so I have done a lot of test stand running. To start a larger glow engine on a free flight model I also mounted an electric starter on a stool with a foot pedal switch. The plane needs to be balanced, sprayed with clear dope, and DT system installed.

Witch Hawk 500

Starter with Foot Pedal Switch

For this season I had put additional clear dope on my Basic Yeller PeeWee 30 model and replaced some parts in the PeeWee .020 engine.  It has made several flights this year which looked really good. I have ready to fly now a ½ A Streak powered by a K&B .049. The motor has been run several times and the plane test glided, looking forward to first powered test flights.

Basic Yeller Flies Again

1/2 A Streak

That is what I have been doing.

Bill Kuhl

Related Links

https://ideas-inspire.com/viscous-dt-tutorial/  Viscous DT Tutorial

https://youtu.be/iOT6h2BYUDE  DT System Added to Blue Ridge Special

https://youtu.be/1-MtPWp_-Pk  Blue Ridge Special DT Flying Clip

https://volareproducts.com/BUY/index.php?main_page=product_info&cPath=2_18&products_id=1096&zenid=sbum6usvjh0mrjeitpouvm2f11  Blue Ridge Special 2-pack Short Kits